Inclined mercury cell and method of operation



March 7, 1957 A. 1.. BARBATo ETAL 3,308,044

INCLINED MERCURY CELL AND METHOD OF OPERATION Filed May 20, 1966 e SheetsSheet 1 Mamh 1967 A. L. BARBATO ETAL 3,308,044

INCLINED MERCURY CELL AND METHOD OF OPERATION Filed May 20, 1966 6 Sheets-Sheet 5 JEZONEQI ztamfimomav 672 33 vom om amEEsm uat. wzEm l m 3561b EMEES ww 5o 556KB 53155 30153 8 6 W In- 8 W 0 mm 3| m vm H 8 8 M 1 mm m .5 m 2 M 3 mm A1 02 S m o N m 2 E 1 w N M ud lillm. w 3 I. v M I @M B sqm 13V" M 8; M ll mm 8% 3|! mvfl all mm 8% m mm 8% .wo .SN Ali. m I: wi 39 33 9 ALEXANDER LOUIS BARBATO HENRY WILLIAM LAUB GEORG MESSNER v 3 ova a n s "5H 01 BiV'ld HOONV ATTO March 7, 1967 A. L. BARBATO ETAL 3,308,044

INCLINED MERCURY CELL AND METHOD OF OPERATION Filed May 20, 196 6 Sheets-Sheet 6 United States Patent ()1 3,308,044 INCLINED MERCURY CELL AND METHGD F OPERATION Alexander Louis Barbato, Perry, and Henry W. Laub, Painesville, Ohio, Georg Messner, Milan, Italy, and Richard Eric Loftlield, Chardon, Ohio, assignors to ()rouzio de Nora Impianti-Elettrochimici, Milan, italy, a corporation of-Italy Filed May 20, 1966, Ser. No. 560,032 20 Claims. (Cl. 204-125) This application is a continuation-in-part of our copending applications Serial Nos. 234,454 and 234,287, both filed on October 31, 1962, and both now abandoned, and relates to improvements in the design, construction and operation of electrolysis cells of the so-called horizontal mercury type.

In the horizontal mercury cell as described, for example, in United States Patent No. 2,544,138, mercury or mercury amalgam flows over the cell base from end to end of the cell forming a flowing mercury cathode, the anodes, usually consisting of graphite, are suspended above the flowing mercury cathode, an electrolyte occupies the space between the anode surfaces and the cathode, and electrolysis of the electrolyte takes place in the electrolyte gap formed between the anode and the cathode surfaces.

In normal use, the base of the cell, over which the mercury cathode flows, is inclined just sufficiently to cause the mercury to flow by gravity from one end of the cell base to the other, the normal inclination from a horizontal plane passing through the high end of the cell being about 0.23 with a maximum inclination in practice of less than As the mercury or mercury amalgam flows from the entrance to the discharge end of the cell under electrolysis conditions, for example in the electrolysis of sodium chloride to produce chlorine and caustic soda, sodium is deposited in the flowing mercury cathode and as the mercury flows toward the discharge end of the cell more and more sodium is amalgamated therein, the amalgam becomes more viscous, the flow becomes more sluggish and the mercury amalgam layer becomes somewhat thicker toward the discharge end of the cell. The mercury has a laminar flow, with sodium being amalgamated in the upper layer. In the normal operation of the horizontal mercury cell the mercury film is maintained at a minimum thickness of about .125 inch (about 3 mm.) and in order to avoid short circuits between the anode surfaces and the surface of the mercury cathode a minimum electrolyte gap of .140 inch has been found to be necessary.

We have discovered that when a horizontal type mercury cell is operated with the cell base at an inclination of about 2 to about 85 from the horizontal, preferably 3 /2 to 30, so that the mercury and amalgam film flows more rapidly, the thickness of the mercury amalgam film can be reduced to about .034 inch (about 1 mm), the electrolyte gap can be reduced to below .10 inch, the voltage reduced, the current efficiency increased, the power consumption per unit of product decreased, and more economical cell operation can be realized. In view of the extensive efforts to improve the economy and operation the horizontal type mercury cell over the last several years, this is a surprising discovery.

We have also discovered that a horizontal type mercury cell, when constructed and operated with the cell base at an inclination of between about 2 to about 85,

preferably about 3 /2" to about as described in the preceding paragraph, has a much higher tolerance to impurities normally encountered in sodium chloride brines, can be operated to produce a higher depletion of the brine and with higher sodium content in the amalgam, and can be operated to produce chlorine and caustic soda without purification of the sodium chloride brines normaliy found to be necessary for electrolysis in a horizontal mercury cell. One reason for this is the greater circulation or agitation of the brine within the flooded cell box as will be described later.

We are aware that mercury cathode cells such as described, for example, in United States Patents Nos. 2,230,023 and 2,688,594 have been designed and operated at substantial inclinations to the horizontal. These, how ever, are diaphragm cells used in the electrolysis of sodium sulfate to produce sodium hydroxide and sulfuric acid, and have not led to the discovery of the improved construction and methods of operation of essentially chlorine-caustic cells of the horizontal flowing mercury I cathode type hereinafter described. While the normal horizontal mercury cells having an inclination of 023 to 0.5 are operated with a gas release space over the entire electrolyte, between the surface of the electrolyte and the cell top, our improved cell is operated as a flooded cell with the electrolyte in contact with the cell cover except for a small gas release space at the upper edge of the inclined cell where the top and the upper end wall intersect.

One of the objects of our invention is to improve the operating efficiency of the horizontal type mercury cell, and decrease its cost of construction and maintenance.

Another object of our invention is to reduce the voltage requirements, increase the current efficiencies and reduce the power consumption in a horizontal type mercury cell.

Another object of our invention is to increase the inclination of the cell base of a flowing mercury cathode electrolysis-cell so as to establish and maintain more uniform thickness of the mercury amalgam layer from end to end of the cell.

Another object of our invention is to decrease the electrolyte gap between the anodes and thecathode surface of a flowing mercury cathode electrolysis cell to thereby increase its power efliciency and reduce the cost of producing electrolysis products therefrom.

Another object of our invention is to operate at greater current densities and thereby increase the quantity of product obtained from a given number and size of cells.

Another object of our invention is to provide an inclined plane mercury cell which can be operated to produce higher depletion of brine in its passage through the cell, which can be operated with higher sodium content in the amalgam and can, if desired, be operated with solid salt addition to the cells instead of brine addition.

Another object of our invention is to provide an electrolysis cell of the flowing mercury cathode type in which advantage is taken of the gas lift effect of the gas bubbles produced at the anodes to cause violent agitation and circulation of the electrolyte within the cell to provide substantially uniform temperature and substantially uniform composition of the electrolyte throughout the cell, from end to end thereof.

Another object of this invention is to utilize the agitating and circulating effect of the gas bubbles released at the anodes of such a cell, to carry solid impurities, such as broken off particles of the anodes or any other solid impurities out of the cell with the depleted brine, where they can be removed by filtration or settling.

Another object of this invention is to use the agitation and circulation of the electrolyte, caused by the gas bubbles released at the anodes, to cause circulation of the electrolyte over the surface of the mercury amalgam adjacent the discharge end of the cell to redissolve any calcium, magnesium or similar metals which have been plated out on the surface of the amalgam.

- A more specific object of our invention is to provide a flowing mercury cathode electrolysis cell in which the base slopes at a substantial angle from the horizontal, the angle being from about to about 85, preferably about to about 30, whereby the speed of mercury flow is increased, to slope the anodes at substantially the same angle whereby gas bubbles are more readily released and swept on the under surface of the anodes, and to enclose the top of the cell, above the anodes with a cover which slopes upwardly toward the gas discharge end of the cell to provide a substantial space for electrolyte above the anodes and below the sloping cover and to maintain the cell substantially filled with electrolyte so that only a small gas space, adjacent the gas and spent brine'outlet, is provided in the region of the uppermost edge of the cell whereby the path of travel of the gas bubbles released at the anodes has a substantial component in both a horizontal and vertical direction through the electrolyte to provide an agitating and circulating effect in the electrolyte before escaping into the gas space.

- Various other objects and advantages of our invention will become apparent as this description proceeds.

Electrolysis cells of the type herein described may be used for various purposes such as the electrolysis of alkali metal salts and other materials. In the following description, the construction and operation of our improved cell in the electrolysis of sodium chloride to produce chlorine and sodium amalgam will be described as one embodiment of our invention. It will be understood, however, that this is only for the purpose of illustration and that the same apparatus and process may be used for the electrolysis of lithium, potassium, cesium and rubidium chlorides and bromides, for the electrolysis of barium and strontium chlorides and bromides, for the electrolysis of other salts which undergo decomposition under the electrolysis conditions which are produced in a flowing mercury cathode electrolysis cell and for other purposes, and that modifications of the preferred method and apparatus may be made within the scope of our invention.

In the accompanying drawings which illustrate a preferred embodiment of our invention:

FIG. 1 is a diagrammatic longitudinal sectional view of a preferred type of unit cell construction;

FIG. 2 is a diagrammatic view illustrating the inclinations at which our improve-d cell may be operated;

FIG. 3 is a graph illustrating the reduction in cell voltage with reference to current density as the inclina tion of the cell is increased from 0.23 to 60 from the horizontal;

FIG. 4 is a graph illustrating the cathode current ethciency, the reduction in voltage requirement, and hydrogen evolution resulting from decreasing the electrolyte s p:

FIG. 5 is a graph illustrating the reduction in cell voltage requirements with increased cell inclinations, at various cathode current densities;

FIG. 6 is a graph illustrating the increase in current efficiency, the decrease in voltage requirements, the reduction in power consumption, and the hydrogen evolution when the cell is operated at inclinations of about 2 to about 30 from the horizontal;

FIG. 7 is a diagrammatic illustration of another embodiment of an inclined plane mercury cell, inclined about from the horizontal, illustrating the gas lifting effect of the gas bubbles released at the anodes in promoting circulation of the electrolyte longitudinally of the cell;

FIG. 8 is a diagrammatic perspective plan view of a similar cell with diagonally slotted or grooved anodes illustrating one embodiment of anode design permitting side to side or transverse circulation effect of the gas bubbles released at the anodes;

FIG. 9 is a cross-sectional view of a slotted graphite anode taken substantially along the line 9 of FIG. 8, and

FIG. 10 is a perspective view of a diagonally corrugated metallic anode.

In the cell embodiment illustrated in FIG. 1 a single unit cell inclined about 15 below the horizontal is shown. The base plate 1, which may be of steel or nickelclad steel or any other suitable conducting material, provides a surface 2 over which a mercury amalgam film 15a, from the mercury pool 15 in the inlet box 10, flows from the inlet to the discharge end of the cell. Toward its lower or discharge end 3 the plate 1 is given an increased inclination of about 40 greater than the inclination of main portion of plate 1 to maintain or facilitate the separation of impurities from the mercury at this point, and the mercury amalgam is in direct contact with the end 3 so as to maintain the mercury under cathodic protection. in. the end zone. This inclination will vary with the inclination of the main portion of plate 1. For all cells of less than 15 inclination, the increased inclinations at the discharge end is preferably of the order of 40. For cells with greater inclination of the main portion of plate 1 the increased inclination at the discharge end should be less than40 and as illustrated in FIG. 2 the end box or discharge end need not have any increased inclination, but should have some means to change the directional angle of the amalgam flow, as described in greater detail in our co-pending application Serial No. 234,309, filed October 31, 1962.

The top of the cell is a box-like cover member 5 from which the anodes 7 are suspended by supports 9 which act as conductors of current from the top of cover member 5 to the anodes '7, suitable bus bar connections (not shown) connect the top of cover member 5 with the positive pole of a DC. current source and the bottom of plate 1 to the negative pole, so that in operation DC. current flows through cover 5, supports 9, anodes 7 and through the electrolyte filling the cell and across the electrolyte gap g between the bottom surface of anodes 7 and the top of the mercury film 15a on the plate 1. The inside of the cover 5, and the sides of supports 9, are covered with an insulating layer 31 of rubber or other suitable insulating material and all other portions of the cell, not intended to be conducting are similarly covered with insulation. The cell is kept completely filled with electrolyte except for a small gas release space adjacent the gas release openings 2d at each side of the cell.

In operation, mercury, substantially stripped of its sodium content in a denuding chamber, continuously flows into the mercury inlet box 10 from the supply line 11 and through a narrow throat provided by an adjustable gate 13 and over the top of plate It to the discharge outlet 25 forming the cathode at the bottom of the cell. The height of the gate 13 is adjustable by means of plastic or non conducting bolts 17 to control the width of the mercury throat and cause uniform distribution of mercury over the top of plate 1 from side to side thereof: however, any other means for securing uniform distribution of the mercury over the top of plate 1 may be used.

Brine enters the cell through openings 19 near the mercury discharge end of the cell and depleted brine and chlorine gas flows out through openings 20 at the upper end of the cell. The location of the brine inlet openings is not critical and the brine may be fed into the cell at either end or near the center of the cell. The cell is preferably kept filled with brine to the level of openings 20. A mercury or amalgam pool 23 is maintained at a level about even with the joint between the cover 5 and base 1 by the upward curvature of the discharge tube 25, and the amalgam in this pool is in direct contact with the extension 3 of base plate 1. If desired, the size and surface area of the amalgam pool 24 may be reduced by an insulated adjustable filler 21 extending from side to side of the cell and adjustably secured to the end wall In of the base 1 by adjustment bolts 27.

The anodes 7 may be adjustably spaced from the surface of the mercury film 15:: by an insulated adjustable spacer 29 located in the joint between cover 5 and base 1. Different thickness spacers 29 may be used to give different anode gaps. Many parts of the cell, customarily used in horizontal mercury cell construction, have been omitted for simplicity of illustration but will be understood by persons skilled in the art to be used in our cell construction.

FIG. 2 illustrates the cell inclinations which may be used in the operation of our invention. In this figure the horizontal plane passing through the top, or mercury entrance end of plate 1, is illustrated by the line H, and various inclinations of the cell between about 2 and about 85 from the horizontal are illustrated by the dotted lines I. The cell, in full line, being indicated at an inclination of about 5 from the horizontal plane. The preferred inclinations are between about 2 where the beneficial effects hereinafter described begin to manifest themselves and about 30, where, in a six foot long inclined plane oell ripples, which may cause short circuiting, may begin to appear in the amalgam film 15a toward the discharge end of plate 1. However, ripple formation does not occur in shorter cells until higher inclinations are reached and it is not intended that the practice of our invention be limited to a maximum of 30 inclination of the cell or to any particular length or width of cell. The preferred inclination for cells of a length of 6 feet or over, is between about 5 and about 20.

FIGURES 3 to 6 illustrate the results of tests conducted on inclined plane mercury cells, under different conditions specified therein. In FIG. 3 the reduction in cell voltage at current densities of 1 to 8 amperes per square inch (a.s.i.) with different degrees of cell inclination are shown. The line A shows the cell voltage required at different current densities with horizontal mercury cells of normal construction, having an electrolyte gap of .140 inch at the normal inclination of less than 0.5 Inclinations of 0.23 to 1 are considered to be equivalent and line A illustrates the cell voltage versus current densities at all inclinations between 0.23 and 1.

Lines B, C and D show that with the electrolyte gap reduced to .094 inch, increasing the inclination of a horizontal type mercury cell from less than 1 to 60 reduces the voltage requirements at all cathode current densities between 1 and 8 a.s.i. At a current density of 5 a.s.i. the reduction in voltage requirement between a normal horizontal mercury cell with a normal electrolyte gap of .140 inch and a normal inclination of .23 and an inclined plane cell with an electrolyte gap of .094 inch and an inclination of between 5 and 30 amounts to approximately .30 volt. This reduction in voltage requirement for the same output of chlorine, other conditions remaining substantially the same, will result in a substantial reduction in the power consumption per ton of chlorine produced. It is not necessary, however, to reduce the electrolyte gap below .14 inch to realize many of the advantages of our invention, as will be obvious from the following description.

Other advantages of our invention are illustrated by FIGS. 4, 5 and 6.

Thus, FIG. 4 shows that as the electrolyte gap is reduced from .14 inch to approximately .05 inch the voltage requirement is redu-ced from approximately 4.6 volts to approximately 4.2 volts while the current efiiciency is reduced only about 1% and the hydrogen evolution is not significantly increased. The several separate tests on which the graphs of FIG. 3 and FIGS. 4 and 5 and 6 are based were conducted on different sizes of inclined plane experimental cells and on anodes of different configuration and hence do not precisely coincide, but for comparison purposes show the type of improvements in operation of the horizontal mercury cell which may be secured by the practice of our invention.

FIG. 5 illustrates the reduction in cell voltage at different current densities as the cell inclination is increased from less than 1 (023 to 1) to 70. Thus, at a cathode current density of 5 a.s.i. the voltage requirement for a normal horizontal mercury cell (023 to 1 inclination and an electrolyte gap of 0.140 inch) under the operating conditions shown, line A, is 5.3 volts, whereas at a 30 inclination and an electrolyte gap of .094 inch, line D, the voltage requirement is only about 4.4 volts. With the same electrolyte gap of .094 inch, the voltage reduction between lines B and D is approximately .7 volt. As the cell of our invention, inclined between about 2 and about can be operated at much higher current densities, 8 a.s.i. or higher, it will be seen from FIG. 5 that even higher reduction in voltage requirements at higher current densities may be realized.

FIG. 6 shows that as the inclination of the cell base from the horizontal is increased from 0.23 (the normal inclination of a horizontal mercury cell) to angles of between about 2 and about 30 from the horizontal, and the electrolyte gap is reduced from 0.140 inch to approximately 0.094 inch (which becomes possible without danger of short circuiting when the cell angle exceeds 2 from the horizontal) the voltage requirements are reduced, in the examples shown, from approximately 4.7 volts to approximately 4.4 volts, the current efiiciency is increased from about 96% to in excess of 98% and remains substantially constant at this figure at cell inclinations of between about 5 and 15, the power consumption is reduced from about 3325 to about 3075 kilowatt hours per ton of chlorine (kw.h./ton C1 and the hydrogen evolution remains low.

In the embodiment of our invention illustrated in FIG. 7 the cell base 101 is illustrated as sloping about 15 below the horizontal. Mercury flows into the mercury feed box 102 from an inlet line 103 and flows in a thin film 104 to the outlet box from which it flows as a sodium mercury amalgam through the outlet 106 to a decomposer (not shown).

Above the base 101 a cover box 107 is provided, from which the anodes 108 are suspended by conducting supports 109. The anodes 108 may be adjusted by adjustably spacing the cover box 107 from the base 101 by means of insulating gaskets of different thickness. The faces of anodes 108 are parallel with and have the-same slope as the base 101 and are uniformly spaced from the mercury film 104 flowing thereover. The top of cover box 107 is preferably parallel with the base 101 and is spaced suificiently above the anodes 108 to provide ample space for electrolyte circulation above and around the anodes 108. The top of cover box 107 need not, however, have exactly the same slope as the base 101. It may slope upwardly at a different angle or even slope in the opposite direction to the slope of the cell base.

The sides, ends and inside top of the cover box 107 and also the sides of the anode supports 109 are covered with an insulating layer 110 of rubber or other suitable insulation, and all other interior parts of the cell which come into contact with the electrolyte, with the exception of the conducting faces of the anodes and the cathode, are similarly covered with insulation.

Due to the high agitation of the electrolyte in the cell the saturated electrolyte may be introduced at any desired point. It is illustrated as being introduced through openings 111 near the lower end of the cell. The. depleted electrolyte and chlorine flow from the upper end of the cell through the openings 112. It is not essential that the electrolyte be introduced near the lower end of the cell, but we prefer to do so. However, it is necessary that-the cell be maintained substantially full of electrolyte and we prefer to maintain the electrolyte level substantially as indicated at 113 so that not only is the electrolytic gap between the anodes 108 and the flowing mercury cathode 104 kept filled with electrolyte, but a substantial depth of electrolyte is maintained above the mercury inlet box 102 as indicated by the space 114 betwen the horizontal line 114a indicating the electrolyte level and the horizontal line 1141) indicating the top level of the mercury in box 102 at the upper end of the cell. The maintenance of a substantial depth of electrolyte above the mercury pool flowing into the cell, provides a path for electrolyte circulation upwardly through the cell above the top of the anodes 108, along the underside of cover box 107, through the pool 114 across the top of the cell and downwardly through the gap between the bottom of the anodes 108 and the top of the mercury film 104 as indicated by the arrows in FIG. 7, as well as up one side and horizontally across the top of the cell and down the other side, as indicated by the arrows in PEG. 8, where diagonally slotted or corrugated anodes are used. It also protects the mercury from contact with the chlorine bubbles at the point where it enters the cell.

Opening 117 closed by plugs 117:: may be provided for flushing out the cell. Positive and negative bus bar connections are indicated at 113 and 119. A spacer 121 in the outlet box 105 extends transversely to the cell and controls the width of the amalgam pool in the mercury outlet box 105 and reduces the amount of mercury necessary to be maintained in the outlet box 105 and also reduces the amalgam surface of the pool which is in contact with the brine and solid impurities. The cover 1%? is insulated from the base 1&1 by rubber or other insulation 122 which may be in the form of insulating gasket spacers. The mercury level in the outlet box 105 is maintained slightly below the level indicated by the goo'seneck shape of the outlet 1195 because of the hydrostatic head of the brine in the cell and the amalgam pool is in direct contact with the extension of the cell base 101 to maintain the amalgam in the pool under cathodic protection In the operation of a cell of the type illustrated in FIG, 7, as the roof, base and anodes in this particular embodiment are essentially parallel to each other and as each cell is essentially an inclined box completely filled with electrolyte, except for the gas space at the upper edge above the electrolyte level 113, when a direct current is passed through the electrolyte between the faces of anodes 1118 and mercury film 1%, in the electrolysis of sodium chloride, for example, sodium ions from the electrolyte are reduced at the amalgam-cathode film 104.- and enter the amalgam, and chloride ions are oxidized to chlorine at the anode faces 108 forming gas bubbles under the anodes. The gas bubbles b migrate along the faces of the anodes, or in the case of grooved anodes fiow into and through the grooves, to the edges of the anodes and rise through the electrolyte to the gas space c above the electrolyte level 113. The inclination of the anode faces at about 2 to about 85, preferably 5 to 30 to the horizontal facilitates the flow of the gas bubbles along the underface of the anodes and when the gas bubbles b break away from the edges of the anodes they rise with both a vertical and a diagonal component of movement, through the electrolyte above the anodes to the gas space 0 at the upper corner of the cell box. The gas bubbles released along the sloping faces of the anodes 108 and migrating upward in the electrolyte induce circulation to the brine which tends to sweep the anode faces free of bubbles and prevent gas blanketing and maintain the area of conductivity of the anodes substantially undiminished.

As the gas bubbles released adjacent the lower end of the cell travel diagonally upwardly toward the chlorine and depleted electrolyte outlets 112, they encounter other gas bubbles released at the edges of anodes 108 further up the cell and all along the cell from the bottom to the top thereof gas bubbles rise vertically and travel diagonally along the underneath side of cover box 107 toward the upper edge or corner of the cell giving a lift effect which provides violent agitation of the entire electrolyte. Observation of an electrolyte in the process of electrolysis, through sight glasses introduced into the side of an experimental cell shows that the electrolyte is maintained in a state of violent ebullition and is filled with small bubbles travelling vertically and diagonally therethrough similar to water boiling over .a hot flame.

In addition to the violent agitation of the electrolyte produced by the gas bubbles b the mercury film flowing downward over the cell base 101 provides a downward component of motion, part of which is transferred to the electrolyte, and as there is a substantial depth of electrolyte indicated by the numeral 114 maintained at the upper end of cell 101, the electrolyte tends to be swept upwardly by the gas bubbles along the underside of cover box 107 and downwardly along the flowing mercury film 104 as indicated by the arrows in FIG. 7, to provide constant agitation of the electrolyte as well as circulation of the electrolyte through the gap between the anodes 108 and the flowing mercury film 104.

This circulation is further promoted by the gas lifting efiiect of the bubbles b which tend to reduce the effective density of the liquid above the anodes, causing the denser liquid which remains after the gas bubbles have escaped into the gas space c-to flow back downward along the mercury surface on the top of cell base 101, the whole effect being to provide a violently agitated and circulating electrolyte. Measurements of the electrolyte temperature and composition along the entire length of the cell show no difference in temperature or composition which can be detected by the ordinary methods of measurement.

Where diagonallyslotted or diagonally grooved or corrugated anodes are used as indicated in FIGS. 8, 9 and 10 the gas bubbles migrate from the lands into thegrooves 126 of the anodes and then escape from the upper edges of the grooves 126 into the space 127 along the side of the cell illustrated in FIG. 8. Perforated anodes such as illustrated in FIGS. 16 and 17 of our copending application Serial No. 234,309, filed October 31, 1962, may be used to facilitate the escape of chlorine bubbles through the anodes. Due to the gaslift effect and the fact that the more dense brine migrates toward the down-stream end of grooves 126, namely, the side 128 of the cell illustrated in PEG. 8, a horizontal rotary component of motion, as illustrated by the arrows in FIG. 8, is impressed upon the vertical, rotary motion illustrated by the arrows in FIG. 1 to produce the following effects.

(1) To maintain uniform electrolyte temperature and concentration from end to end of the cell. (2) To reduce localized depletion of brine under the anodes. (3) To scrub the gas bubbles from under the anodes and increase the brine circulation below the anodes so that all of the anode faces are continually in use and the building up of areas of high current density which raise voltage is prevented. (4) Due to their prompt removal, the chlorine bubbles do not displace the brine at the face of the anodes and ample electrolyte is available for the passage of current. (5 The immediate removal of the gas bubbles from beneath the anodes helps prevent recombination of the cell products and thereby increases current efficiency of the cell. (6) The brine agitation keeps small foreign particles suspended in the brine where they will not be deposited on the amalgam surface and detract from the cell operation and will be automatically removedfrom the cell by the brine circulation.

In addition to the-above advantages of the high brine agitation and circulation the volume of gas space in the upper corner of the cell is very small and as the cell produces very little hydrogen and much of the gas space 0 is filled with a foamy mixture of chlorine and brine, the probability of explosion is much less than in 9 horizontal or vertical mercury cells, which have a much larger volume gas space.

FIGS. 8 and 9 illustrate slotted graphite anodes and FIG. illustrates a titanium anode 130 with a platinum electrode face 131 shaped with grooves 132 therein. The grooves 132 may be formed to run diagonally of the anode or at right angles to the edges thereof. Perforated or expanded metal anodes may be used if desired.

The cell box cover may slope upwardly at a different angle than the angle of the base 101 and may slope in the opposite direction to the slope of base 101, the essential characteristics being that the cover slopes upwardly toward the gas discharge space and that the space between the anodes and the cover be filled with electrolyte so that the gas bubbles move upwardly through the electrolyte with both a vertical and a diagonal component of motion whereby agitation and circulation of the electrolyte is brought about by the movement of the gas bubbles.

As the inclination of the experimental cell in the examples shown was increased to 30, the current efliciency decreased due to the formation of ripples on the amalgam surface, which touched the anode and caused intermittent short circuiting. However, where the mercury is controlled to prevent ripple formation, the cell inclination can be increased beyond 30 and the eificiencies shown in FIG. 6 can still be realized.

The results of our discovery show that at a inclination of a horizontal type mercury cell, over the normal inclination of .23 for cells of this type, these cells can be operated at a cell voltage approximately 0.30 volt less than the normal horizontal cell when both cells are operated at a current density of 5 amperes per square inch, that the inclined plane cell of our invention can be operated satisfactorily at current densities of 1 to 8 a.s.i. (see FIG. 3), that the 15 inclined plane cell, when operated with purified brine operates with a current efiiciency of approximately 98.5% as compared with a current efiiciency of 96% for the normal horizontal mercury cell, and with a slightly lower hydrogen content in the cell gas. When commercial graphite anodes, slotted 1%" x A, are used as in FIG. 5, the voltage reduction (between lines A and D) is even greater than the voltage reduction (between lines A and D) when special anodes slotted /4" x A" are used as illustrated in FIG. 3. Our cell at 15 inclination can operate on unpurified brine at 98% current efiiciency and produce only 0.7% H in the cell gas.

In addition to these advantages, as the mercury film in our incline plane cell is less than /3 to A the thickness of the mercury film required in a horizontal mercury cell operated at cell inclination of 0.23", the mercury inventory in our cell, per unit of cell capacity, is correspondingly reduced. The thickness of the mercury film in a normal horizontal mercury cell is about A, whereas the thickness of the mercury film in an inclined plane cell with an inclination of 15 is less than at its thickest point. As the inclination of the cell is varied, the thickness of the mercury film may be varied from less than to about The thickness of the mercury film in an inclined plane cell diiiers at various points along the cell depending upon the cell inclination, the mercury flow rate, the distance from the mercury inlet and other factors. The inclined plane mercury cell of our invention can be operated with brine depletions of up to 100 grams per liter (NaCl) with substantial uniformity of the brine composition from end to end of the cell. This gives substantially uniform anode wear, substantially uniform temperature, substantially uniform brine composition throughout the cell and other operating advantages.

To show the comparison between a normal horizontal mercury cell having an inclination of 023 and inclined plane cells of the type herein described at inclinations of 5, 15 and 30, the following runs were made.

Example I .-Operating conditions (1) Cell inclination 0.23. (2) Cathode current density 5.0 a.s.i. (3) Brine depletion 60 g.p.l. (4) Brine type Purified brine. (5) Cell temperature -5 F. (6) Mercury flow rate 3000 mls./rnin., per ft.

The current efficiency during the run was 96.3%, the cell voltage was 4.68 volts, the power consumption was 3333 kwh./ ton C1 and the hydrogen evolution was .35% of the cell gas on an air-free basis. Had this cell been operated on an unpurified brine the hydrogen evolution would have exceeded the explosive limits.

Example II.Operating conditions 1) Cell inclination 5.

(2) Cathode current density 5.0 a.s.i.

(3) Brine depletion 60 g.p.l.

(4) Brine type Purified brine.

(5) Cell temperature 160i5 F.

(6) Mercury flow rate 3000 mls./min., per ft. of cell Width, .15% Na in amalgam.

(7) Anodes Graphite, slotted type,

/2" blades with A" gas spaces, slots perpendicular to mercury flow. (8) Length of run after equilibrium conditions reached 5 /2 hours. (9) Electrotyle gap 0.094".

The current efficiency during the run was 98.3%, the cell voltage was 4.42 volts, the power consumption was 3084 kwh./ ton C1 and the hydrogen evolution was .43% of the cell gas on an air-free basis. As shown by the following Example VI, this cell when operated at a 5 and 15 inclination will tolerate high'impurity content of the brine without dangerous hydrogen evolution and the loss of efiiciency which accompanies high hydrogen evolution.

Example IlI.Ope/'ating conditions (1) Cell inclination 15.

(2) Cathode current density 5.0 a.s.i.

(3) Brine depletion 60 g.p.l.

(4) Brine type Purified brine.

(5) Cell temperature l60- -5 F.

(6) Mercury flow rate 3000 mls./n1in., per ft. of cell width, .15% Na in amalgam.

(7) Anodes Graphite, slotted type,

/2" blades with A gas spaces, slots perpendicular to mercury flow. (8) Length of run after equilibrium conditions reached 4 /2 hours. (9) Electrolyte gap 0.094".

The current efficiency during the run was 98.4%, the

cell voltage was 4.43 volts, the power consumption was 3088 kwh./ ton C1 and the hydrogen evolution was .24%

of the cell gas on an air-free basis. As shown by the following Example VI, this cell when operated at a and inclination will tolerate a high impurity content of the brine without dangerous hydrogen evolution and the loss of efficiency which accompanies high hydrogen evolution.

Example I V.Operating conditions (1) Cell inclination (2) Cathode current density 5.0 a.s.i.

(3) Brine depletion 60 g.p.l.

(4) Brine type Purified brine.

(5) Cell temperature l60i5 F.

(6) Mercury flow rate 3000 mls./min., per ft. of cell width, .15% Na in amalgam.

(7) Anodes Graphite, slotted type,

/2" blades with A" gas spaces, slots perpendicular to mercury flow. (8) Length of run after equilibrium conditions reached 5 /2 hours. (9) Electrolyte gap 0.094".

The current eificiency during the run was 96.1%, the cell voltage was 4.39 volts, the power consumption was 3133 kWh/ton C1 and the hydrogen evolution was .44% of the cell gas on an air-free basis. As shown by the following Example V, a cell of this type when operated at a 30 inclination will tolerate high impurity content of the brine without dangerous hydrogen evolution and the loss of efiiciency which accompanies high hydrogen evolution.

Example V To show the effect of the inclined plane mercury cell of our invention in tolerating brine impurities and automatically removing brine impurities from the cell a run was made, wherein a purified sodium chloride brine was electrolyzed in a cell, as described hereinabove, and the amount of hydrogen in the gas produced in the cell was determined. Thereafter, a number of impurities were added to the brine, one at a time, and the cumulative effect of these impurities, in terms of hydrogen production, was determined.

The cell inclination was 30, the cathode current density was 5.0 -a.s.i., the brine depletion was -50 g. p.l., the impurity content of the brine was varied during the run, the cel temperature was 140-l50 F., the mercury fiow rate was 4000 mls./rnin., per foot of cell width with 20% Na in amalgam, and the anodes were graphite, slotted /2 blades, A" gas spaces with slots perpendicular to the mercury flow.

The purified brine used for the initial run had the following compositions:

NaCl-3 10 g.p.l.

Mg-3.1 ppm.

Ca To-o small to measure SO -Less than 3.0 g.p.1. Ni-Too small to measure Cu-Too small to measure Fe0.6 ppm.

The amount of hydrogen produced in this run, using this purified brine, was less than 0.5% of the volume of the cell gas produced. Thereafter, various quantities of impurities were added to the brine, one at a time, and after each addition the effect of each impurity on the hydrogen evolution in the cell was determined. In each case the amount of impurities added was sufiicient to give the brine the indicated concentration of the impurity. Using this procedure, 1@ following results were obtained:

Impurity Concentration Eifect in Brine 200 ppm No increase in H3 evolution. 200 p.p.n1 o. 10 p.p.n1 H2 evolution increased to about 15 g.p l..- N0 furthcr increase in H2 evoluon. 10 plp.m Do. 5 ppmg Do.

From these results it is seen that the cell of the present invention has an extremely high tolerance to impurities in the sodium chloride brine feed. This high tolerance to the impurities makes it possible to operate this cell without the necessity of subjecting the brine to an extensive purification before it is introduced into the cell and without the necessity for careful monitoring and frequent manual purging of the cell. The runs of this example were conducted with an electrolyte gap of 34 for experimental purposes but the results would have been about the same with the electrolyte gap at 0.094.

Example VI To further show the ability of our inclined plane mercury cell to tolerate impurities in the brine and even to be fed with solid unpurified run of the mine rock salt, a run was made in which the brine was repeatedly resaturated with solid sodium chloride. The cell inclination was 5 and 15, the cathode current density was 5.0 a.s.i., the electrode gap was 0.094, the brine depletion was 60 g.p.l., the brine was varied during the run, the cell temperature was maintained at 160i5 F., the mercury how rate was 3000 mls./min., per foot of cell width, with .15% Na in the amalgam, and the anodes were graphite slotted /2" blades, A gas spaces, with the slots perpendicular to the mercury flow.

This run was continued for a period of four days during which time the N-aCl brine passed through the cell was resaturated about 113 times with no dechlorination, pH adjustment or purge. The run was started with a cell inclination of about 5 below the horizontal which was increased to about 15 during the run. The brine used has a NaCl content of about 300 grams/liter. The impurities in the brine initially, were as follows:

Grams/ liter Ca++ 1.25 M g++ 0.03 S0 2.4 Fe 0.001 Insolubles 2.75

The brine was resaturated during the run with solid NaCl having the above impurities to maintain the NaCl content at 300 grams/ liter.

Under these conditions the analysis of the feed brine after various numbers of resaturations was as follows:

Grams/Liter Number of pH Resaturations NaCl Mg Ca Fe No'rE.SO4= content remained substantially unchanged. i.e. about 2.6 grams/liter.

The hydrogen content of the cell gas, after 1001l2 resaturations, was about 0.7%. Additionally, the cur-rent efficiency of the cell during this run averaged 97.5%.

These results show that, during the course of this run, the major impurities in the brine with the exception of Mg++ reached the saturation point. Notwithstanding this fact, the cell continued to operate with low hydrogen evolution and high current efliciency. This shows that the present cell can be etficiently operated, even using a brine which is saturated with Ca++, S05, and Fe impurities and can be fed with solid unpurified salt.

For simplicity of illustration only those parts of the cell necessary to illustrate its operation have been shown in diagrammatic form. Many parts, well known to persons skilled in the art, have been omitted. The cell illustrated may take various forms, within the spirit of our invention and the scope of the following claims.

What we claim is:

1. The method of operating a horizontal-type, flowing mercury cathode electrolysis cell, having a stationary base, an inclined top, anodes and a flowing mercury cathode With an electrolyte gap and no diaphragm between the anodes and the cathode, said base, top and anodes being spaced from each other with the base and anodes substantially parallel with each other which comprises maintaining the cell base at an inclination of between about 2 and about 85 from the horizontal, maintaining the electrolyte gap between 0.12 and 0.04 inch, flowing a mercury film of a thickness of below .062 inch by gravity over the base of said cell, flowing an electrolyte through said cell between the anodes and the flowing mercury cathode, filling the cell with electrolyte solution to the top thereof, providing a gas separating space at the upper edge of the inclined cell where the top and end wall intersect and passing an electric current through the electrolyte between said anodes and said flowing mercury cathode, to dissociate said electrolyte into anode and cathode prod ucts, recovering the cathode product in the flowing mercury cathode and recovering the anode pro-duct above the electrolyte level of said cell.

2. The method of operating a horizontal-type, flowing mercury cathode electrolysis cell, having a stationary base, an inclined top, anodes and a flowing mercury cathode with an electrolyte gap and no diaphragm between the anodes and the cathode, said base, top and anodes being spaced from each other with the base and anodes substantially parallel with each other which comprises maintaining the cell base at an inclination of between about 5 and about 30 from the horizontal, maintaining the electrolyte gap between about 0.12 and 0.04 inch, flowing a mercury film of a'thickness of below .062 inch by gravity over the base of said cell, flowing an electrolyte through said cell between the anodes and the flowing mercury cathode, filling the cell with electrolyte solution to the top thereof, providing a gas separating space at the upper edge of the inclined cell where the top and end wall intersect and passing an electric current through the electrolyte between said anodes and said flowing mercury cathode, to dissociate said electrolyte into anode and cathode products, recovering the cathode product in the flowing mercury cathode and recovering the anode product above the electrolyte level of said cell. i

. 3. The method of operating a horizontal-type, flowing mercury cathode electrolysis cell, having a stationary base, an inclined top, anodes and a flowing mercury cathode with an electrolyte gap and with no diaphragm between the anodes aud the cathode, said base, top and anodes being spaced from each other with the base and an odes substantially parallel with each other which com prises maintaining the cell base at an inclination of between about 5 and about 30 from the horizontal, maintaining the electrolyte gap between about 0.12 and 0.04 inch, flowing a mercury film of a thickness of below .062 inch by gravity over the base of said cell, flowing an electrolyte through said cell between the anodes and the flowing mercury cathode, filling the cell with electrolyte solution to the top thereof, providing a gas separating space at the upper edge of the inclined cell where the top and end wall intersect, increasing the rate of amalgam flow adjacent the lower end of the cell and passing an electric 14 current through the electrolyte between said anodes and said flowing mercury cathode, to dissociate said electrolyte into anode and cathode products, recovering the cathode product in the flowing mercury cathode and recovering the anode product above the electrolyte level of said cell.

4. The method of reducing the voltage, increasing the current eificiency and reducing the power consumption of an essentially horizontal-type rectangular diap-hragmless mercury cathode electrolysis cell having a cell top, anodes and a stationary cell bottom over which the mercury cathode flows, which comprises maintaining the cell bottom at an inclination of between about 2 and about from a horizontal plane, maintaining the anodes substantially parallel with the cell bottom, providing an electrolyte gap between the anodes and the cell bottom, flowing mercury by gravity over the inclined cell bottom from the high end to the low end to provide a flowing mercury cathode. flowing an electrolyte solution through said cell, filling the cell with electrolyte solution to the top thereof, providing a gas separating space at the upper edge of the inclined cell where the top and end wall intersect and passing an electrolyzing current directly through the electrolyte in said gap from the anodes to the cathodes to decompose said electrolyte solution.

5. The method of reducing the voltage, increasing the current eflicency and reducing the power consumption of an essentially horizontal-type diaphragmless mercury cathode electrolyss cell having anodes and a stationary cell bottom over which the mercury cathode flows, which comprises maintaining the cell bottom at an inclination of between about 5 to about 20 from a horizontal plane, maintaining the anodes and the cell top parallel with the cell bottom providing an electrolyte gap between the anodes and the cell bottom, flowing mercury over the inclined cell bottom from the high end to the low end to provide a flowing mercury cathode, flowing an electrolyte solution through the cell, maintaining the cell substantially filled with electrolyte except for a gas release space at the upper edge thereof and passing an electro lyzing current directly through the electrolyte in said gap from the anodes to the cathode to decompose said electrolyte solution.

6. The method of reducing the voltage, increasing the current efiiciency and reducing the power consumption of an essentially horizontal-type diaphragmless mercury cathode electrolysis cell having anodes and a stationary cell bottom over which the mercury cathode flows, which comprises maintaining the cell bottom at an inclination of between about 2 and about 85 from a horizontal plane, maintaining the anodes and the cell top parallel zith the cell bottom, flowing mercury over the inclined cell bottom from the high end to the low end to provide a flowing mercury cathode, providing an electrolyte gap of between 0.05 and 0.12 inch between said anodes and said flowing mercury cathode, flowing an electrolyte solution through said cell and passing an electrolyzing current directly through the electrolyte in said gap from the anodes to the cathode to decompose said electrolyte solution.

7. The method of reducing the voltage, increasing the current efliciency and reducing the power consumption of an essentially horizontal-type diaphragmless mercury cathode electrolysis cell having anodes and a stationary cell bottom over which the mercury cathode flows, which comprises maintaining the cell bottom at an inclination of between about 5 and about 30 from a horizontal plane, maintaining the anodes and the cell top parallel with the cell bottom, flowing mercury by gravity over the inclined cell bottom from the high end to the low end to provide a flowing mercury cathode, providing an electrolyte gap containing only an electrolyte solution between said anodes and said flowing mercury cathode, flowing an electrolyte solution through said cell, filling the cell with electrolyte solution to the top thereof, providing aeoaoaa a gas separating space at the upper edge of the inclined cell where the top and end wall intersect and passing an electrolyzing current through the electrolyte in said gap from the anodes to the cathode to decompose said electrolyte solution.

8. The method of reducing the voltage, increasing the current efficiency and reducing the power consumption of an essentially horizontal-type diaphragmless mercury cathode electrolysis cell having anodes and a stationary cell bottom over which the mercury cathode flows, which comprises maintaining the cell bottom at an inclination of between about 2 and about 85 from a horizontal plane, maintaining the anodes and the cell top parallel with the cell bottom, flowing mercury by gravity over the inclined cell bottom from the high end to the low end to provide a flowing mercury cathode, maintaining the mercury film on said cell bottom below 0.062 inch in thickness, providing an electrolyte gap containing only an electrolyte solution between said anodes and said flov ing mercury cathode, flowing an electrolyte solution through said cell and passing an electrolyzing current through the electrolyte in said gap from the anodes to the cathode to decompose said electrolyte solution.

9. The method of reducing the voltage, increasing the current cfi'lciency and reducing the power consumption of an essentially horizontal-type diaphragmless mercury cathode electrolysis cell having anodes and a stationary cell bottom over which the mercury cathode flows, which comprises maintaining the cell bottom at an inclination of between about 5 and about 30 from a horizontal plane, maintaining the anodes and the cell top parallel with the cell bottom, flowing mercury by gravity over the inclined cell bottom from the high end to the low end to provide a flowing mercury cathode, maintaining the mercury film on said cell bottom below 0.062 inch in thickness, providing an electrolyte gap of between 0.05 and 0.12 inch containing only an electrolyte solution between said anodes and said flowing mercury cathode, flowing an electrolyte solution through said cell, filling the cell with electrolyte solution to the top thereof, providing a gas separating space at the upper edge of the inclined cell where the top and end wall intersect and p g an electrolyzing current through the electrolyte said gap from the anodes to the cathode to decompose said electr-olyte solution.

10. The method of reducing the voltage, increasing the current efllciency and reducing the power consumption of an essentially horizontal-type diaphragmless Inercury cathode electrolysis cell having anodes and a stationary cell bottom over which the mercury cathode flows, which comprises maintaining the cell bottom at inclination or" between about 5 and about 30 from a horizontal plane, maintaining the anodes and the cell top parallel with the cell bottom, lowing mercury by gravity over the inclined cell bottom from the high end to the low end to provide a flowing mercury cathode, maintaining the mercury film on said cell bottom below 0.062 inch in thickness, increasing the inclination of the cell bottom adjacent the discharge end thereof to facilitate separation of impurities from the mercury, providing an electrolyte gap of between 0.05 and 0.12 inch containing only an electrolyte solution between said anodes and said flowing mercury cathode, flowing an electrolyte solution through said cell, filling the cell with electrolyte solution to the top thereof, providing a gas separating space at the upper edge of the inclined cell where the top and end wall intersect and passing an electrolyzing current through the electrolyte in said gap from the anodes to the cathode to decompose said electrolyte solution.

11. The method of providing uniformity of composition and temperature in an electrolyte used in a diaphragmless horizontal-type flowing mercury cathode electrolysis cell, which comprises providing an essentially box type cell structure with a base, cover, and anodes between said cover and said base, said base, cover and anodes being spaced from each other and substantially parallel to each other, maintaining said cell tilted at an angle of about 2 to about to the horizontal, filling said cell with electrolyte substantially to the upper edge thereof, flowing mercury over the inclined cell base to form a flowing mercury cathode, passing an electrolysis current through said electrolyte between said anodes and said cathode, and causing the gas bubbles generated by the electrolysis of said electrolyte to flow vertically and diagonally upward through said electrolyte above the anodes and along the bottom side of said tilting cover to the upper edge of said cell to agitate and circulate the electrolyte therein, and discharging the gas bubbles adjacent said upper edge.

12. The method of providing uniformity of composition and temperature in an electrolyte used in a diaphragmless horizontal-type flowing mercury cathode electrolysis cell, which comprises providing an essentially box type cell structure with a base, cover and perforated anodes between said cover and said base, said base, cover and anodes being spaced from each other and substantially parallel to each other, maintaining said cell at an angle of about 2 to about 85 to the horizontal, filling said cell with electrolyte substantially to the upper edge thereof, maintaining a substantial depth of electrolyte over the entire base of said cell to permit recirculation of the electrolyte, flowing mercury over the inclined cell base to form a flowing mercury cathode, passing an electrolysis current through said electrolyte between said anodes and said cathode, and causing the gas bubbles generated by the electrolysis of said electrolyte to flow vertically and diagonally upward through said electrolyte above the anodes to the upper edge of said cell to agitate the electrolyte therein, and circulate said electrolyte up- Ward along the cover of said cell and downward along the base by the lifting effect of said gas bubbles.

13. The method of providing uniformity of composition and temperature in an electrolyte used in a diaphragmless horizontal-type flowing me cury cathode electrolysis cell, which comprises providing an essentially box type cell structure, with a base, top and anodes between said top and said base, said base, top and anodes being spaced from each other and substantially parallel to each other, maintaining said cell at an angle of about 5 to 30 to th horizontal, filling said cell with electrolyte substantially to the upper edge thereof, flowing mercury over the inclined cell base to form a flowing mercury cathode, passing an electrolysis current through said electrolyte between said anodes and said cathode, and cansing the gas bubbles generated by the electrolysis of said electrolyte to flow vertically upward through said electrolyte and diagonally upward along the underfaces of said anodes and the underside of said cell top to the upper edge of said cell to agitate and circulate the electrolyte therein and maintain the composition and temperature of the electrolyte uniform from end to end of said cell.

lid. The method of providing uniformity of composition and temperature in an electrolyte used in a diaphragmless horizontal-type flowing mercury cathode electrolysis cell, which comprises providing an essentially box type cell structure with a base, top and anodes between said top and said base, said base, top and anodes being spaced from each other and substantially parallel to each other, maintaining said cell at an angle of about 5 to 30 to the horizontal, filling said cell with electrolyte substantially to the upper edge thereof, maintaining a substantial depth of electrolyte over the entire base of said cell to permit re-circulation of the electrolyte, flowing mercury over the inclined cell base to form a flowing mercury cathode, maintaining a substantial depth of electrolyte over the mercury at the mercury inlet and of said cell, passing an electrolysis current through said electrolyte between said anodes and said cathode, and causing the gas bubbles generated by the electrolysis of said elec- 1 L trolyte to flow vertically upward through said electrolyte and diagonally upward along the underfaces of said anodes and the underside of said cell top to the upper edge of said cell to agitate the electrolyte therein, to circulate said electrolyte upward along the top of said cell and downwardly along the base by the lifting effect of said gas bubbles, to maintain the composition and temperature of said electrolyte uniform throughout said cell.

15. The method of providing uniformity of composition and temperature in an electrolyte used in a diaphragmless horizontal-type flowing mercury cathode electrolysis cell which comprises providing an essentially box type cell structure with a base, top and diagonally slotted anodes between said base and said top, said base, top and anodes being substantially parallel to each other and the anodes being spaced from the base and the top, maintaining said cell at an angle of about 2 to about 85 to the horizontal, filling said cell With electrolyte substantially to the upper edge thereof, flowing mercury over the inclined cell base to form a flowing mercury cathode, maintaining a substantial depth of electrolyte over the mercury layer at the upper end of said cell, passing an electrolysis current through said electrolyte between said anodes and said cathode, and causing gas bubbles generated by the electrolysis of said electrolyte to flow along said diagonal grooves in said anodes and vertically upward through said electrolyte above the anodes and diagonally upward along the underside of said cell top to the upper edge of said cell to agitate and circulate the electrolyte therein and maintain the composition and temperature of the electrolyte uniform throughout said cell.

16. The method of providing uniformity of composition and temperature in an electrolyte used in a diaphragmless horizontal-type flowing mercury cathode electrolysis cell which comprises providing an essentially box type cell structure with a top, and diagonally slotted anodes substantially parallel to each other and with theanodes spaced from the base and the top, maintaining said cell at an angle of about 5 to about 30 to the horizontal, filling said cell with electrolyte substantially to the upper edge thereof, flowing mercury over the inclined cell base to form a flowing mercury cathode, maintaining a substantial depth of electrolyte over the mercury layer at the upper end of said cell, passing an electrolysis current through said electrolyte between said anodes and said cathode, and causing gas bubbles generated by the electrolysis of said electrolyte to flow along said diagonal grooves in said anodes and vertically upward through said electrolyte above the anodes and diagonally upward along the underside of said cell top to the upper edge of said cell to agitate and circulate the electrolyte therein and maintain the composition and temperature of the electrolyte uniform throughout said cell.

17. The method of providing uniformity of composition and temperature in an electrolyte used in adiaphragmless horizontal-type flowing mercury cathode electrolysis cell, which comprises providing an essentially box type cell structure with a base, top and anodes substantially parallel to each other and the top spaced a substantial distance above said anodes, maintaining said cell at an angle of about 2 to about 85 to the horizontal, filling said cell with electrolyte substantially to the upper edge thereof, flowing mercury over the inclined cell base to form a flowing mercury cathode, passing an electrolysis current through said electrolyte between said anodes and said cathode, and causing the gas bubbles generated by the electrolysis of said electrolyte to flow vertically and diagonally upward through said electrolyte above the anodes to the upper edge of said cell to agitate and circulate the electrolyte therein.

18. The method of promoting the removal of gas bubbles from the anode faces of an inclined plane mercury cell, having an essentially box type cell structure, with a base, a top and anodes spaced between said base and top, which comprises maintaining the cell base and the anodes at an angle of about 2 to about from the horizontal, maintaining the anodes and the cell base substantially parallel, substantially filling the cell above and below said anodes with electrolyte, flowing mercury over the cell base to form a cathode, passing an electrolysis current between said anodes and said cathode and utilizing the circulating effect of the gas bubbles released at the anode faces and the inclination of said anode faces to cause circulation of the electrolyte and remove gas bubbles from the anodes.

19. The method of promoting the removal of gas bubbles from the anode faces of an inclined plane mercury cell, having an essentially box type cell structure with a base, a top and anodes spaced between said base and top, which comprises maintaining the cell base and the anodes at an angle of about 5 to about 30 from the horizontal, maintaining the anodes and the cell base substantially parallel, substantially filling the cell above and below said anodes with electrolyte, flowing mercury over the cell base to form a cathode, passing an electrolysis current between said anodes and said cathode and utilizing the circulating effect of the gas bubbles released at the anode faces and the inclination of said anode faces to cause circulation of the electrolyte and remove gas bubbles from the anodes.

20. The method providing uniformity of composition and temperature in an electrolyte used in a horizontaltype flowing mercury cathode electrolysis cell having an essentially box type cell structure with a base, a top and anodes spaced between said base and top which comprises maintaining the cell base and anodes substantially parallel and tilted at an angle at which mercury will flow from end to end of said cell base, tilting the top of said cell at an angle of about 5 to about 30 from the horizontal, filling said cell above and below said anodes with electrolyte substantially to the upper edge of said tilted top, so that the electrolyte contacts the cell top substantially to the upper edge thereof, leaving a gas discharge space at the upper edge of said cell, flowing mercury over said cell base to form a cathode, passing an electrolysis current between said anodes and said cathode and utilizing the gas bubbles released at the anode faces and ris ing along the inclination of said cell to said gas discharge space to cause circulation and discharging the gas from said gas space at the upper edge of said tilted cell top.

References Cited by the Examiner UNITED STATES PATENTS 2,688,594 9/1954 Oosterman 204-219 2,704,743 3/1955 Deprez 204-219 2,848,406 8/ 1958 Szechtmann 204219 JOHN H. MACK, Primary Examiner.

H. M. FLOURNOY, Assistant Examiner. 

1. THE METHOD OF OPERATING A HORIZONTAL-TYPE, FLOWING MERCURY CATHODE ELECTROLYSIS CELL, HAVING A STATIONARY BASE, AND INCLINED TOP, ANODES AND A FLOWING MERCURY CATHODE WITH AN ELECTROLYTE GAP AND NO DIAPHRAGM BETWEEN THE ANODES AND THE CATHODE, SAID BASE, TOP AND ANODES BEING SPACED FROM EACH OTHER WITH THE BASE AND ANODES SUBSTANTIALLY PARALLEL WITH EACH OTHER WHICH COMPRISES MAINTAINING THE CELL BASE AT AN INCLINATION OF BETWEEN ABOUT 2* AND ABOUT 85* FROM THE HORIZONTAL, MAINTAINING THE ELECTROLYTE GAP BETWEEN 0.12 AND 0.04 INCH, FLOWING A MERCURY FILM A THICKNESS OF BELOW .62 INCH BY GRAVITY OVER THE BASE OF SAID CELL, FLOWING AN ELECTROLYTE THROUGH SAID CELL BETWEEN THE ANODES AND THE FLOWING MERCURY CATHODE, FILLING THE CELL WITH ELECTROLYTE SOLUTION TO THE TOP THEREOF, PROVIDING A GAS SEPARATING SPACE AT THE UPPER EDGE OF THE INCLINED CELL WHERE THE TOP AND END WALL INTERSECT AND PASSING AN ELECTRIC CURRENT THROUGH THE ELECTROLYTE BETWEEN SAID ANODES AND SAID FLOWING MERCURY CATHODE, TO DISSOCIATE SAID ELECTROLYTE INTO ANODE AND CATHODE PRODUCTS, RECOVERING THE CATHODE PRODUCT IN THE FLOWING MERCURY CATHODE AND RECOVERING THE ANODE PRODUCT ABOVE THE ELECTROLYTE LEVEL OF SAID CELL. 